Friend or Foe: The Nature of interaction between Saprophytic Protists and Phytoplankton in Coastal Ecosystems

Responsible: Hanna Strindberg

E-mail: hannstri@student.ibv.uio.no

Supervisors: Adriana Lopes dos Santos, Wenche Eikrem and Micah Dunthorn

Aim

This research aims to advance our understanding of the ecological role of Labyrinthulomycetes and their impact on Diatom populations.

Background

Plankton communities are vital components of marine ecosystems. They consist of a diverse group of microorganisms functioning as producers, consumers and recyclers (Richardson & Schoeman, 2004). Autotrophic algae are incredibly vital members of these communities because they can utilize energy from sunlight, fix carbon dioxide (CO₂) from the atmosphere and create organic material that builds the fundaments of the marine food web. Within this realm of autotrophic algae, Diatoms emerge as particularly significant. They alone are accountable for approximately 20% of Earth's photosynthetically fixed CO₂ and can contribute up to 75 % in coastal ecosystems (Leblanc et al., 2012).

While abiotic factors do have significant influence on individual species, its crucial to acknowledge the importance of interaction between microbial species within coastal plankton communities. A particularly intriguing relationship observed is between Diatoms and a group of saprophytic protists known as Labyrinthulomycetes (Bjorbækmo et al., 2020). These unicellular eukaryotes exhibit a diverse array of characteristics and play significant roles in marine ecosystems. For instance they are known as the causing agent of Eelgrass wasting disease (Muehlstein et al., 1991). However, the nature of their interactions with Diatoms remains poorly understood. Exploring these dynamics within coastal plankton communities will help us understand their implications for ecosystem resilience and sustainability.

Research Questions

1. How do Labyrinthulomycetes isolates form the Oslofjord contribute to shaping the protist communities within coastal ecosystems?
2. What is the nature of relationship between Diatoms and Labyrinthulomycetes? Does the interaction lean towards parasitism or mutualism?
3. How can Labyrinthulomycetes be effectively isolated and cultured in a media free from fungal contamination?